WO1985003904A1

WO1985003904A1 - Hot runner-type injection molding device

Info

Publication number: WO1985003904A1
Application number: PCT/JP1985/000091
Authority: WO
Inventors: Itsuo Shibata; Tetsuo Uchida
Original assignee: Ju-Oh Trading Co., Ltd.
Priority date: 1984-02-28
Filing date: 1985-02-27
Publication date: 1985-09-12
Also published as: DE3590090T; JPS61197215A; US4726751A; DE3590090C2; JPH0550371B2; JPS61197216A; CH668220A5; JPH0433253B1

Abstract

A hot runner-type plastic injection molding device in which the resin temperature near the gates of a metal mold having a plurality of cavities is precisely controlled to obtain a good gate balancing, without using a mechanism for opening and closing valves or a mechanism for intermittently heating the gates, and without causing threading or clogging in the gates. Resin paths adjacent to gates of cavities are formed in the shape of a pipe that can be heated by the high-frequency induction. Coils for high-frequency induction heating are wound round the resin paths, and are connected in series with each other to high-frequency power supply means which is controlled by power control means.

Description

Specification

Hot runner type injection molding equipment

Technical field

The present invention relates to a plastic injection molding apparatus, particularly to a hot runner complete injection molding apparatus.

Background technology

The resin filled in the resin passage connecting the nozzle of the molding machine and the cavity of the mold, that is, the resin (product) filled in the cavity with a so-called runner The runner is melted in a so-called cold runner forming system, which is cooled and solidified so that when the mold is opened, the product is discharged out of the mold together with the mold. While maintaining the state, only the resin in the cavity is cooled and solidified and discharged out of the mold, and the runner in the molten state is transferred to the carrier in the next molding cycle. 2. Description of the Related Art A hot runner complete injection molding system designed to fill a cavity is known.

In such hot runner type injection molding, the problem of "cutting" of the resin at the gate portion when the mold is opened is a problem. That is, the resin path from the nozzle of the molding machine to the gate of each cavity is ripened from the outside by a resistance ripening heater, and the resin is melted. Although it is known that the resin passage is kept close to the gate hole, the resin passage is generally always cooled by cooling water. Because of the close proximity to the cavity plate, the rinsing rate fluctuates greatly with the opening and closing operations of the mold, making it extremely difficult to keep the resin temperature near the gate hole constant. There was a problem that the resin pulled through the thread and the resin solidified and clogged the gate hole, making it impossible to perform the next injection. If the resin is too long, a so-called “washout” phenomenon occurs in which the resin becomes shallow from the gate hole during mold opening.

In order to solve such a problem, a mechanical valve is provided in the gate portion, and the valve near the gate is ripened sufficiently to keep the resin in a molten state, and the valve is closed when the mold is opened. A device was developed to prevent stringing and avalanche of resin. There is a drawback that failures are liable to occur because of having to do so. There is also a disadvantage that the device becomes large due to the use of a valve having a complicated structure.

In the resin passage near the gate hole, a pointed ripening body is arranged so as to extend into the gate hole, and when the mold is opened, the resin in the gate hole is actively cooled and solidified. However, the resin from the gate hole at the time of opening the mold does not become shallow, and stringing is prevented, and the heating element is ripened immediately just before the next cycle and solidifies in the gate hole. There is also known a so-called hot-runner type injection molding machine of the so-called konomi-maturation type, which re-melts the resin so that injection becomes possible, but in this device, the solidified resin in the gate is used. It takes time to re-dissolve the resin. For this reason, there are various problems such that the injection pressure is remarkably impaired, and particularly when molding with a resin containing glass fiber, the tip of the ripened body is damaged or worn. Also, if sufficient heat is applied to the tip of the heating element in order to instantly re-melt the solidified resin in the gate, the base of the ripening body will inevitably be higher than the tip. There is also the problem that the resin around the base is burned or decomposed due to the high temperature.

In addition, all of the conventional hot runner type injection molding machines use a heat transfer from a resistive ripening heater to ripen a desired heated portion, for example, a gate hole. Therefore, it is extremely difficult to control the heating part to a desired temperature due to its poor response, especially for a large number of units with multiple cavities. In the case of molds, it was difficult to equalize the temperatures of the gate holes of the cavities (so-called maintenance of gate balance). Has the drawback that disconnection frequently occurs due to self-resistance maturation.

Purpose of the invention

In view of the above-described circumstances, the present invention can control the resin temperature near each gate hole of a mold having a plurality of cavities with high accuracy, and can provide a good gate rose. Therefore, stringing, barrenness, clogging of the gate, etc. can occur without using a complicated mechanism such as opening and closing the valve, intermittent heating of the gate hole, etc. The purpose of the present invention is to provide a hot runner complete injection molding apparatus capable of performing excellent molding. -I

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Disclosure of the invention

In the hot runner type injection molding apparatus of the present invention, each key of a resin passage (generally comprising a sprue part and a runner part) connecting a nozzle of a molding machine and each cavity in a mold. The portion of the cavity adjacent to the gate hole is formed by a pipe-shaped member made of a material that can be heated by low frequency induction ripening. A 髙 -frequency induction ripening coil is wound around each of the pipe-shaped members, and the ripening coils are connected in series with each other to 髙 -frequency power supply means. Further, control means for controlling the temperature of the pipe-shaped member by controlling the electric power supplied to the ripening coil is provided.

When a low-frequency current is supplied to the ripening coil from the power supply means, the pipe-shaped member is ripened by electromagnetic induction. Ripening the pipe-shaped member due to the heat generated by the electromagnetic induction has a better responsiveness than heating by ripening transmission from a resistance heating heater. In other words, in the case of heat conduction from the heater, when the temperature of the pipe-shaped member reaches a predetermined temperature, the heater is heated to a higher temperature, and power is supplied to the heater. The temperature of the pipe-shaped member continues to increase even after the gas stops, or the temperature of the pipe-shaped member decreases even if the heater is turned on when the temperature of the pipe-shaped member decreases. There is a delay due to the ringing phenomenon that continues, but in the case of induction ripening, the pipe-like material itself generates heat, and furthermore, it generates heat. Since the speed is high, there is no risk of ringing, and the angle control can be performed very well. In addition, in the case of heat conduction from the heater, the degree of return of the heated member is large due to the contact between the heater and the member to be aged (pipes). However, in the case of heating by electromagnetic induction, the minute positional relationship between the coil and the member to be heated hardly affects the toughness of the member to be heated. The resin temperature in the vicinity of each gate hole can be controlled with high precision, and the gate balance can be reduced easily. Further, since the induction-ripening coil is a simple wire wound, it can be wound to a position substantially close to the gate hole, and accordingly, the gate of the pipe-shaped member can be wound. Since it is possible to directly generate heat up to a portion substantially close to the hole, the temperature difference between the tip of the pipe-shaped member (the portion close to the gate hole) and the base β (the portion away from the gate hole) is determined. The temperature of the base rises too much when the tip is ripened to a temperature sufficient to keep the resin in the gate hole in a molten state. There is no such thing as the resin in contact with that part being burned or decomposed, and if each heating coil is connected in series, for example, one aging coil due to aging Changes in the resistance of the coil circuit affect the current flowing through all the heating coils. The gate balance is particularly easy to maintain because of the gagging, that is, when each ripening coil is connected to the power supply in parallel, the resistance of one ripening coil circuit is large for some reason. As the power gets smaller, less power is applied to the coil La

Only the temperature of the wound pipe-shaped member decreases, but if it is connected in series, the power applied to all the ripening coils will be small, and therefore all the pipe-shaped members will be cooled. The temperature will decrease almost uniformly, and the gate balance will be extremely low and easy to maintain. According to experiments, it is sufficient that the number of turns of each heating coil is from several turns to 10 turns, and when each coil is connected in parallel to a power supply, the load is small. There is a problem that power is difficult to enter. Furthermore, the heat generated by the 髙 -frequency induction ripening coil also depends on the distance from the power supply to the coil, that is, the resistance loss of the line including the skin effect, so when connecting each coil to the power supply in parallel If the distance from the power supply of each coil is exactly matched, or if the number of windings, etc., is not reduced in consideration of the difference in the distance from each power supply to the coil, the gate balance will be lost. In this respect, too, the fc device is advantageous in that each coil is connected to the power supply in series. Furthermore, as described above, in the apparatus, the resin near the gate hole is ripened by simply winding a few turns to a few turns of wire around the pipe-shaped member. As a result, the structure around the gate is simplified. Therefore, according to the apparatus of the present invention, a hot runner of a mold having a large number of small products or a mold having several fc gates for one cavity is required. Can be easily realized. As the temperature control means for controlling the temperature of the pipe-shaped member to a desired value, the temperature of the pipe-shaped m-material is detected, and the heating coil is supplied from the power supply means in accordance with a difference from a set value. Adjust or turn on the power supplied to You can use a circuit that turns off.

As is well known, if the temperature of the resin near the gate hole can be controlled with high accuracy, resin leakage from the gate hole does not occur when the mold is opened, and the gate is clogged. It is easy for a person skilled in the art to find a critical resin temperature which does not cause the resin to melt, and thus the valve which opens and closes mechanically depending on the equipment. In addition, good hot runner molding can be performed without using a complicated mechanism such as intermittent heating. Also, unlike the above-mentioned intermittent ripening molding equipment, there is no need to arrange a ripening period inside the resin passage, so that the injection pressure is not reduced and the heating element is damaged. There is no equipment failure. In addition, the heating coil used in the device has little self-resistance heat generation, so there is no risk of disconnection, and it has frequently occurred in conventional hot runner type molding devices. There is almost no downfall due to heater disconnection.

In one embodiment of the present invention, a gate balance adjusting circuit can be connected in parallel to each of the ripening coils.

A capacitor coil or a resistor can be used as the gate / parameter adjustment circuit. For example, if a condenser is connected in parallel to several of several ripening coils in parallel with each other, the mixing of the pipe-shaped member around which the ripening coils are wound increases. However, the temperature of the pipe-shaped member around which another heating coil is wound decreases. When a coil or a resistor is connected in parallel to each of several ripening coils in parallel with each other, the heating coil is wound around a pipe-shaped member. The temperature drops and another heating coil is wound The temperature of the pipe-shaped member increases. In addition, the magnitude of the temperature at that time changes depending on the value of the gate impedance adjustment circuit.

Therefore, by selectively connecting a gate impedance adjustment circuit in parallel to some of the plurality of ripening coils and selecting the values of the elements, the entire gate garden is selected. It can be fine-tuned by increasing the gate balance.

If a resistor is used as the gate-parameter adjustment circuit, power loss occurs, and in that regard, a capacitor or a coil is more desirable.

Further, since the hot runner complete injection molding apparatus according to the present invention described above uses high frequency power, it generates noise when measuring the temperature of the tip of the pipe-shaped member using a thermocouple. However, if a thermocouple is used to prevent noise from being picked up, the structure around the gate becomes complex, resulting in a reduction in size.

That is, the maturation power of a mature couple (for example, CA) is very small at several 771 V, and 髙 In a high-frequency magnetic field of output, the SZN ratio becomes extremely poor due to induction, making accurate temperature detection difficult. It is desirable that the vicinity of the gate of the pipe-shaped member be thin (about 7 Φ), but if a thermocouple is used for this purpose, the thickness of the thermocouple is also reduced to about 0.5 Φ (outer sheath). Although it has become thinner, the electrical resistance will be higher. As is well known, the higher the electrical resistance, the easier it is to pick up noise. Including compensation guidance -?-It is difficult to completely cut the noise even if a mature couple is shielded.

In view of the above, in another preferred embodiment of the present invention, the high frequency power is periodically stopped, for example, every 0.5 sec, for a predetermined time, for example, 1 OB sec, and stopped during that time. A switching means for reading the output of the temperature detecting means is provided.

In such a device, when reading the output of the temperature detecting means, the high frequency power is turned off, and therefore the temperature can be accurately detected without being affected by the high frequency magnetic field. it can.

In still another preferred embodiment of the present invention, the return control means receives a temperature signal from the temperature detection means for detecting the temperature of the pipe-shaped member, especially the temperature at the tip thereof, and By controlling the power supplied to the ripening coil to control the temperature of the pipe-shaped member to a desired temperature, a large amount of power is supplied to each ripening coil in response to a signal from the molding machine. O Only supply at the time of the o

According to such an apparatus, the resin temperature in the vicinity of the gate hole is usually maintained at a sufficiently low level so that resin leakage or stringing does not occur from the gate hole, and the temperature is set immediately before injection. After ripening, the resin near the gate hole can be melted and injected. By doing so, the accuracy required for temperature control is reduced, and in particular, properties such as viscosity, such as nylon, change significantly within a small width of the resin mixture, and therefore, In addition, when the mold is opened, there is no resin leakage or stringing from the gate hole, and the gate is clogged during injection. This is particularly advantageous when molding resins that have an extremely narrow range of global resin temperatures that will not cause -ιο-. Furthermore, by setting the above-mentioned desired degree of attainment (hereinafter referred to as “steady resin grip”) at a temperature sufficiently lower than such an industrial temperature, the surrounding conditions of each gate hole can be adjusted. Even when the resin temperature is slightly different for each gate hole due to the difference, there is no occurrence of a trap such as stringing or shallow resin.

The timing and time for supplying the high power to each heating coil vary depending on molding conditions, molding cycle, type of resin, etc. It is desirable to adjust so that it melts to the extent that it can be injected.

In order to return the resin temperature (mixing degree of the pipe-shaped member) to the steady resin mixture after the injection, each ripening coil was used until the resin grip (force of the pipe-shaped member) returned to the normal resin temperature. The power supply to the pipes may be stopped only, or a cooling medium passage may be provided around the pipe-shaped member to actively cool the cooling medium. It may be provided integrally with the member, or a pipe with good ripening properties may be closely wound around the pipe-shaped member, and a cooling medium such as water may pass through the inside. Alternatively, each ripening coil may be formed by a hollow pipe-shaped conductor, and a cooling medium may be passed through the inside.

Further, the ripening means calculates the temperature of the pipe-shaped member and the rate of change of the degree of attraction, and from the relationship of the rate of change of the degree of return to the degree of return, the above-mentioned induction is performed. -//-It is desirable to have a short-cut detection means to detect short-cuts of the induction ripening coil. This is because when the high-frequency induction ripening coil is short-cut, the change in electric resistance is almost negligible due to the small number of turns of the coil and the low electric resistance. In addition, it is very difficult to electrically detect this short-circuit. That is, the short-circuit detecting means is provided in a desired temperature range in which the pipe-shaped member is controlled by the humidity controlling means. At some point, if the temperature drops rapidly, or if the temperature falls below the above-mentioned range, or if the rate of increase is below a certain value, the shot detection means will be used. This is to determine that a short shot of the coil has occurred, and this makes it possible to reliably detect a shot that was electrically difficult.

In yet another preferred embodiment of the present invention, a coil assembly for providing an insulating layer between the induction heating coil and the pipe-like member and for holding the induction heating coil is provided. The outer wall of the mold is in contact with the mold. An air insulation layer is preferred as a maturing layer.

In this way, the induction heating coil is kept at a relatively low temperature by restricting the transfer of heat from the pipe-shaped member by the air aging layer and dissipating the ripening to the mold. Thus, the deterioration of the coil surface layer can be prevented.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view showing an injection molding apparatus according to one embodiment of the present invention, FIG. 2 is a sectional view showing a part of the apparatus shown in FIG. 1 in detail, Fig. 3 shows another example of how to wind a ripening coil, Fig. 4 shows an example of a method for fixing a ripening coil, and Fig. 5 shows a modification of the device in Fig. 1. Diagram,

FIG. 6 is a flowchart illustrating a part of the operation of the control circuit of the apparatus shown in FIG.

7 to 11 are cross-sectional views each showing a modification of the vicinity of the chip of the apparatus shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, a hot runner type injection molding apparatus according to one embodiment of the present invention is provided with a mold 10 having four cavities 12a, 12b, 12c, 12d. The mold 10 is composed of a fixed half 14 fixed to a fixed die plate of a molding machine (not shown) and a movable half 16 fixed to a movable plate. When the side half 16 is pressed against the fixed half 14, that is, when the mold 10 is closed, the four cavities 12 a to 12 d are formed between the half halves 14 and 16. It is becoming. The fixed half 14 has a mounting plate 18 attached to the fixed die plate 18, a manifold block 22 pressed and fixed to the mounting plate 18 with a heat insulating material 20 interposed therebetween, and It is composed of a cavity plate 26 which is pressed and fixed to the manifold block 22 with the support block 24 interposed therebetween.

The cavity plate 26 is provided with four concave portions 28a, 28b, 28c, 28d which open to the movable half 16 side. These four The recesses 28a to 28d form the four cavities 12a to 12d together with the four cores 17a, 17b, 17c, and 17d provided on the transfer side half 16. An opening is formed on the manifold block side of the cavity plate 26 so as to face the four recesses 28a to 28d, respectively, on the manifold block side. Four recesses 30a, 30b, 30c, 30d are provided. In the fixed side half 14, a nozzle (not shown) of the molding machine and each of the cavities 12a to 12d are provided with gate holes 32a, 32b formed in the bottom surface of each of the recesses 30a to 30d, respectively. , 32c, and 32d are formed through the resin passage. This resin passage is composed of a so-called sprue part 34a that is directly connected to the nozzle of the molding machine and a so-called runner part 34b that is branched into four parts in the manifold block 22. Portions of the runner portion 34b adjacent to the respective gate holes 32a to 32d are formed by pipe-shaped chips 36a, 36b, 36c, 36d. The ripening coils 38a, 38b, 38c, 38d are wound around each of the chips 36a to 36d, respectively.As will be described in detail later, the ripening coils 38a to 38 (1 When an electric current is passed, each of the chips 36a to 36d ripens.The said manifold block 22 is desirably formed by a suitable j¾l ripening means (not shown). It has been ripened up to the temperature.

Molten resin injected from the nozzle of the molding machine in the same manner as the conventional hot runner type injection molding apparatus is filled into the cavities 12a to 12d through the resin passage. Normally, the key The plate 26 and the movable half 16 are cooled, and after the resin in each of the cavities 12a to 12d is cooled and solidified, the relocated half 16 is retracted. The mold is opened. At this time, the products formed in the cavities 12a to 12d are carried by the cores 17a to 17d of the movable half 16 and are removed from the fixed trailing half 14.

The ripening coils 38a to 38d are connected to the high-frequency power supply circuit 42 in series with each other via the relay pox 40. The power supply circuit 42 is a rectifier circuit 44 for rectifying AC from the AG power supply and converting it to DC (current), an SSR (Solid Steady Relay) 45 for turning on / off the AC power supply, which will be described later. A switching element 46, a translator 48, which repeats opening and closing (on-off) under the control of the temperature control circuit 52, and an fc capacitor C connected in parallel to the primary side of the translator 48, and a filter A circuit 50 is provided so that the four ripening coils 38a to 38d are connected in series to the secondary side of the transformer 48. The imagination control circuit Numeral 52 includes four thermocouples 54a, 54b, 54c, 54d which are brought into contact with the tips of the chips 36a to 36d, respectively, and detect the temperatures of the tips of the chips 36a to 36d. The outputs of the four thermocouples 54a to 54d are input to the secondary amplification circuit 58 by the switching circuit 56. After being amplified, the signal is input to the AZD conversion circuit 60. The temperature information from each of the mating couples 54a to 54d converted by the AZD conversion circuit 60 into digital signals is transmitted to the control circuit 62. It is stored in the memory circuit 64 under control. Further, a set temperature input circuit 66 and a temperature display circuit 68 are connected. The set temperature input circuit 66 inputs the set temperature at the tip of the chip, which is selected by a setting dial or the like, to the control circuit 62.The set temperature is input to the recording circuit 64 under the control of the control circuit 62. It is recorded. The control circuit 62 extracts the temperature information from the thermocouples 54a to 54d once stored in the memory circuit 64, that is, the temperature at the tip of the four chips 38a to 38d at that time, and calculates the temperature. The circuit 70 calculates the 'average value' of the degree of mixing at the tips of the four chips 38a to 38d, and calculates the difference between the average value and the set temperature. The control circuit 62 controls the oscillation circuit 72 according to the magnitude of the difference to change the output signal of the oscillation circuit 72. In the power supply circuit 42 in the present embodiment, the lower the frequency is within the predetermined box, the larger the power heating coils 38a to 38 (1), so that the control circuit 62 The oscillation circuit 72 is controlled so as to oscillate at a lower frequency as the difference between the set value and the average value of the degree of thinking at the tip of the chip is larger. The output signal of the oscillation circuit 72 is amplified by a drive circuit 74 to drive the switching element 46 of the power supply circuit 42. The switching element 46 repeats opening and closing in accordance with the oscillation frequency of the oscillation circuit 72, so that a high-frequency current flows through the primary side of the transformer 48, and a high-frequency current is induced on the secondary side of the transformer 48. And the four ripening coils 38a to 38 connected in series to the secondary side of the transformer 48. High-frequency current is supplied to 38d Heating coils 38a to 38d When a high-frequency current flows, the chips 36a to 36d around which the ripening coil is wound ripen by electromagnetic induction. Of course, each of the chips 36a to 36d needs to be formed of a material that can ripen by high frequency induction ripening. A variety of such materials are known, but as will be apparent to those skilled in the art, each chip 36a-36d must be suitable for pressure and pressure. Therefore, the material must be selected in consideration of such points. In particular, it is desirable to have a material having a large mechanical strength, a large magnetic permeability, and a small temperature dependence of the magnetic permeability even when it is ripened before leakage. Examples of such materials include SKD-61 and 62 for hot dies. The temperature control circuit 52 repeatedly repeats the ratio of the average value of the actual temperature at the tip of each of the chips 36a to 36d input from each of the thermocouples 54a to 54d to the set temperature, and the former is better than the latter. When the difference is small, the oscillation frequency of the oscillation circuit 72 is increased as the difference between the two becomes small. As the oscillation frequency increases, the frequency of the current flowing through the primary side of the transformer 48 also increases, and the frequency of the current supplied to the heating coils 38a to 38d also increases. The electric power supplied to each of the heating coils 38a to 38d is reduced. That is, when the actual mixing at the tip of the chip is lower than the set temperature, the temperature control circuit 52 supplies a large amount of power to the ripening coils 38a to 38d when the difference is large, and the actual temperature is reduced. As the temperature approaches the set temperature, the supplied power is reduced, thereby converging the actual flatness at the tip of the chip to the set grip. Conversely, the actual temperature is set When the temperature exceeds the temperature, the larger the difference is, the larger the power supply is destroyed, and the actual temperature is brought closer to the set temperature. The temperature display circuit 68 displays the actual temperature at the tip of the chip, the difference from the set temperature, and the like. In the apparatus according to the present embodiment in which the chip is ripened by such high-frequency induction heating, the chip 363 is used.

Since 36d itself generates heat, the mature response is faster than ripening the chip by ripening transmission from the resistance heating heater, resulting in ringing ゃ煞 transmission. It is possible to control the chip angle with high accuracy without causing delay.

The SSR 45 is connected to a control circuit 62 and is opened and closed at a predetermined period. For example, it is opened for 10 msec every 0.5 sec. That is, the control circuit 62 stops the output from the power supply circuit 42 by turning on the AC power at a predetermined cycle, and stores the temperature information from the thermocouples 54a to 54d in the meantime. To memorize it. Therefore, the signals of the thermocouples 54a to 54d can be read in the vicinity of the thermocouples 54a to 54d without being affected by the high-frequency magnetic field generated by the ripening coils 38a to 38d. . Note that the period of opening the SSR 45 and the bridge at that time are not particularly limited to the above example, and may be appropriately selected. However, if the period is too long, the temperature detection becomes simple. Is too large, which is not desirable in the control of the mixture, particularly in the apparatus of the present embodiment having a good responsiveness. If the period of opening the SSR 45 is too short, or if the opening time is too long, the time when power is supplied to the ripening coils 38a to 38d becomes shorter. -/ S-tips 36a to 36d take time to ripen to the desired temperature. Therefore, it is desirable to determine the cycle of opening SSR 45 and the holding garden in consideration of these points.

Note that the SSR 45 does not open until the AC power supply voltage goes to zero even when a sword is received from the control circuit 62, and conversely until the AC power supply voltage goes to zero even when a close signal is received. It is desirable to use a zero-cross type SSR that does not close.

Further, the control circuit 62 maximizes the electric power supplied to each of the ripening coils 38a to 38d in response to a signal from a molding machine (not shown), for a predetermined time, as will be described in detail later.

Normally, a microprocessor is used as the control circuit 62. The operation of the microprocessor for performing the above-described control will be described with reference to a flowchart of FIG. I do.

In Fig. 6, the control circuit (microprocessor) 62 first opens the SSR 45 and switches the switch 56 to read the output To of each of the thermocouples 54a to 54d, and averages the values. Calculate MT o. (Step S i> Next, in step S 2, the difference X between the set temperature ST and the average value MTo is calculated, and in step S ₃ , whether the difference X is positive, that is, Determines whether the set temperature ST is higher than the average value MT o.If X> 0, α (≥ 0) corresponding to the absolute value of X is added to the control value C, and the oscillation circuit and outputs 72. (step _{S 4, S 8) x <} 0 when the output absolute planting corresponding to alpha (0) to Ji flashing from the control value C oscillator 72 of the X. (step S 5, S 6> then mold closing start signal from the molding machine at stearyl-up S ₇ to determine whether the inputted. If the mold closing start signal has not been input, the process returns to step S i and strips steps S i to S 7. If the mold closing start signal is input, turn on the timer Τι. (Step Se> This timer Ti determines the timing for maximizing the power supplied to the ripening coils 38a to 38d. The timer T1 increases. other et al (Step-up S _3), the control value C to the maximum output to the oscillation circuit 72. to oN (the scan STEP S) this is the circumferential sometimes Thailand M a T _2. (Step -up S i) this Thailand M a T ₂ are control values C a and the maximum our Ku time, i.e. Nodea Ri also determines the time to Kyoawase full power to the pressurized Jukuko yl 38a ～38D, Thailand mer T ₂ is controlled value C until for up is kept to a maximum. then Thailand M a T ₂ is a you up to (Step-up S i) zero control value C was minimal or (Step S 1) Next, in step S 1, whether the average value MTo of the output To of the shunt couples 54 a to 54 d has fallen below the set value S τ. There is determined. The average value MT o 髙I Ri by the setting value ST 閭 the control value C average value MT o is the phrase low-Ri by setting value ST in. Here is kept to a minimum and stearyl-up S Control returns to ₂ so that the average value MTo converges to the set value ST.

Incidentally, the timer T i to cormorants good mentioned above all SANYO determining the maximum and Suruta Lee Mi ing power to Kyoawase the heating coils 38a to 38 DEG d, timer over T ₂ are the maximum power Determine rush when sustained In consideration of the type of the resin, the steady temperature (the above-mentioned set temperature), the molding cycle time, etc., the resin is set so that the resin near the gate hole can be melted and injected immediately before the injection. In this way, just before the injection, a large current is supplied to the heating coils 38a to 38d so that the injection is possible, so that the steady temperature (set temperature) can be reduced. In addition, the temperature can be set lower than the critical temperature that does not cause avalanche and also does not cause clogging of the gate. Therefore, the requirement for the accuracy of the temperature is relaxed, and the control becomes easier with fc.

In the flowchart shown in FIG. 6, the maximum power is set by maximizing the control value C to make the injection possible state, so that the ripening coils 38a to 38a Although it is designed to be supplied to d, it is not always necessary to supply the maximum power, and it is sufficient to supply enough power to obtain a desired rise in resin temperature. In this case, instead of maximizing the control value C in step SM, the control value C obtained by adding the value (α>) corresponding to the desired resin temperature rise to the previous control value C is used. Then, it may be output to the oscillation circuit 72.

In the flowchart of Fig. 6, the signal from the molding machine was used as the mold closing start signal.However, if the signal is output at a fixed timing during the molding cycle, What kind of signal to use

-Needless to say.

Figure 2 shows the structure around each chip, with tip 36a inverted. -U

This is shown in detail.

As shown in FIG. 2, the tip 36a is a pipe-shaped member provided with a through hole 80 forming a resin passage near the gate hole. The through-hole 80 has a small diameter at the tip end (on the side of the gate hole 32a) and has substantially the same diameter as the gate hole 32a. Annular ridges 82a and 82b are provided on both end surfaces of the chip 36a. The tip 36a is pressed and sandwiched between the garden of the manifold block 22 and the cavity plate 26, and the ridges 82a and 82 are slightly deformed. By doing so, resin leakage from the pressing surface is prevented. Of course, other sealing means such as a ring may be used to prevent the resin from leaking. The protruding ridge 82b on the tip surface reduces the contact area between the tip 3a and the cavity plate 26 so that the tip plate of the tip 36a is connected to the cavity plate 26. It also helps to reduce the amount of ripeness that is robbed. A concave portion 84 into which the tip of the mature couple 54a is inserted is provided near the tip of the tip 36a. The ripening coil 38a and the thermocouple 54a are housed in a case 86 made of a metal having a high frequency shielding effect, and the lead wire 88a and the thermocouple of the ripening coil 38a are further provided. The lead bran 88b of the pair 54a extends to the relay box 40 through the space 90 between the shields integrally connected to the case 86. The ripening coil 38a is made of a metal having good conductivity and being resistant to corrosion, for example, silver, a silver alloy, silver, etc., and an insulating coating overlaid thereon. Normally several turns to several tens of turns depending on the size of the tip It is wound around the tip. At the rear end of the tip 36a, there is a transfer of ripening from the manifold block 22, and on the other hand, from the tip of the tip 36a, the ripening is made by the cavity plate 26. Because it is deprived, it is desirable that the ripened coil 38a be wound as close to the tip of the tip 36a as possible so that the magnetic flux from the coil 38a is concentrated at the tip.

If the tip is long and ripening from the center of the chip is large, the coil should be dense from the tip and sparse from the center to the rear as shown in Fig. 3. May be wound. Whether or not the ripened coil 38a is in close contact with the outer surface of the tip 36a has little effect on the temperature of the tip of the tip 36a, but the length of the tip 36a of the coil 38a is small. Since the position in the vertical direction and the winding density greatly affect the grip at the tip of the tip 36a, it is desirable to fix the coil 38a around the tip 36a. For this, a ripening adhesive or the like may be used. Alternatively, as shown in FIG. 4, a spiral groove 90 is cut on the outer surface of the chip 36a according to a desired winding pattern. Wrap the coil in the groove 9Q.

The relay box 40 includes a connector 100 for connecting a secondary side of the transformer 48 of the high-frequency power supply circuit 42, and a connector 101 for connecting each of the heating coils 38a to 38d. 102, 103, and 104 are provided. The connectors 101, 102, 103, 104 are connected to the connector 100 in series with each other. In addition, each connector 101, 102, 103, 104 Gate balance adjustment connectors-111, 112, 1 13.114 for connecting the gate balance adjustment circuit so as to straddle them (in parallel) are connected. The temperature of each of the chips 36a to 36d can be controlled by connecting the gate balance adjustment circuit to the gate balance adjustment connectors 111 to 114 as appropriate. can do . Fig. 1 shows an example in which capacitors 105 are connected in parallel to heating coils 38a and 38c via gate balance adjustment connectors 111 and 113, respectively. It is shown . In this case, the temperature of the chips 36a and 36c around which the heating coils 38a and 38c are wound rises, and the temperature of the chips 36b and 36d around which the other mature coils 38b and 38d are wound. The temperature drops. If a coil or resistor is used instead of a capacitor as the gate / parallel adjustment circuit, the heating coils 38a and 38c are wound. The degree of thinking of the chips 36a and 36c decreases, and the temperature of the other heating coils 38b and 38 (the chips 36b and 36d around which the coil 1 is wound rises. That is, the condenser and the condenser By selectively connecting gate and balance adjustment circuits, such as coils and resistors, to the ripening coils in parallel, power supply to each ripening coil can be controlled. The distribution can be changed, whereby the chips 36a to 36d are matured by a plurality of ripening coils 38a to 38d connected in series. It is possible to raise and lower the angle separately, which means that the angle is easily reduced by some factor. Also Ri by other pressurized Jukuko Yi Le to have pressurized Jukuko Lee Lumpur and Ruge over to cope with cormorants by a large electric power is Kyoawase Bok bus run-adjust for co-Ne-click _______________________________________________________________________________________________________________________________________________________________________ & ₂ Even if a coil or resistor is connected to the gate-balance adjustment connector corresponding to the heating coil so that the supplied power is smaller than the power supplied to the other heating coil Good. Of course, any combination of capacitors, coils, and resistors can be used. However, if a resistor is used as a gate balance adjustment circuit, power is generated, and in that respect, the other two are more desirable. Needless to say, the effect of the gate balance adjustment circuit increases as the value of the element increases. Therefore, the operator can view the temperature display or check the state of the resin in each gate hole, and connect an element with an appropriate value to an appropriate gate-parameter adjustment connector. Or a plurality of gate-parameter adjusting circuits having different values may be set in advance for each ripening coil in advance so that they can be connected according to the humidity difference between the chips. An element having an appropriate value may be selected for connection.

Further, as shown in FIG. 5, the switching may be automatically performed under the control of the control circuit 62. That is, in the relay port and the sock 40a shown in FIG. 5, each gate balance adjustment connector can be selectively brought into contact with six fixed contacts and one of the six fixed contacts. It comprises relays 121, 122, 123, and 124 having three movable contacts. For each of the relays-1 2 1 to 1 24, 5 of the 6 contacts -^-A different capacitor is connected, and the other contact is open. Each of the relays 121 to 124 is driven by a relay drive circuit 125 controlled by the control circuit 62. The control circuit 62 selectively executes the relays 121 to 124 according to the temperature variation of the four chips 36a to 36 (1 input from the thermocouples 54a to 54 (1) to set the desired value. The relay drive circuit 125 is controlled so that the capacitors are connected in parallel to the corresponding ripening coils 38a to 38d.

Although the lead palm passed through the mold cannot be made too thick for practical use, the resistance loss including the skin effect of the circuit from the power supply circuit to the coil should be minimized. Therefore, it is desirable to use a thick conductor with as low a high-frequency resistance as possible for the line up to the relay box 40, and to arrange the relay box 40 as close to the mold as possible.

In the above embodiment, after injection and this sever the supply of power with minimal control value C in (Thailand mer T ₂ is after U [rho), i.e. the pressurized Jukuko yl 38a ~ 38 (i Therefore, the temperature of the chips 36a to 36d may be positively lowered to the steady temperature by cooling water or the like. As shown in Fig. 7, wrap a cooling medium pipe P around each chip so that it alternates with the heating coil, and pass the cooling medium through the pipe P. Alternatively, as shown by 38a-1 in Fig. 8, the conductor for the ripened coil may be a hollow pipe-shaped lead and a cooling medium may be passed through it. In the latter case, in particular, the structure around the chip can be prevented from becoming complicated, and there is an advantage that oxidation of the bran for the ripening coil can be prevented.

Fig. 9 shows the details of the structure around the chip to prevent the ripening coil from heating. In the figure, the tip 36a has a flange portion 93 at the upper end, and a thickness of about 1 mm is formed between the outer surface 94 of the cylindrical portion below the flange 93 and the ripening coil 38a. The lake is filled with air and the fc air ripening layer 92 is formed. The ripened coil 38a is supported by the case 86 via the filler 91 in this state, and the outer surface of the case 86 is in stark contact with the cavity plate 26.

With this structure, even if the chip 36a is heated by the ripening coil 38a, the chip 36a is ripened by the air-ripening slaughter 92, so that the ripening of the chip 36a In addition, the heating coil 38a is cooled to a relatively low temperature by the water cooling via the soil agent 91 and the case 86 through the heating coil 26a. The ripening of the ripening coil 38a can be released toward the cavity plate 26, keeping the ripening coil 38a relatively low in mixing. You can do that. For this reason, it is desirable that the filler 91 and the case 86 be made of a material having a good conductivity.

Although there may be a problem with the ripening efficiency due to the provision of the air ripening layer 92, the thickness of the air ripening layer 92 is reduced to some extent because the present invention employs high-frequency induction heating using a coil. In --As long as the ripening efficiency decreases, there is almost no problem. Actually, the heating coil has a coil length of 20 mm, a coil inner diameter of 7 mm, and a coil outer diameter of 9 MI. Almost no decline occurs.

As shown in FIG. 10, the inner diameter of the coil 38a is not affected by high-frequency induction ripening. For example, a pipe 95 made of a mother is provided and the filler 91 is charged. You may be sick.

Further, an example in which the case 86 is cylindrical and the entire outer surface contacts the cavity plate 26 is shown above. As shown in A-A section), a part of the outer surface of the case 86 may contact the cavity plate 26.

Also, the tip 36a of the coil assembly (case 86, filler 91, ripening coil 38a, and mica pipe 95) may be separated or may be integrated. Good.

The case 86 is preferably made of a non-magnetic material such as stainless steel or aluminum, and the pitting agent is preferably made of ceramics.

The apparatus of this embodiment has a short circuit detecting means for detecting when the ripening coils 38a to 38d are short-circuited in the control circuit 62. Since the electric resistance of the heating coils 38a to 38d themselves is very small, even when the ripening coils 38a to 38d are short-circuited, the change in the resistance hardly appears, so that the short-circuiting is performed. Is electrically detected based on current, voltage, voltage change, etc. Very difficult to get out. Therefore, in the present invention, the presence or absence of a short is detected based on the temperatures of the tips of the tips 36a to 36d detected by the mature couples 54a to 54d and the rate of change of this temperature. I am trying to do it.

Specifically, the temperature is determined at a predetermined temperature at the tip of the chips 36a to 36d, that is, at a point below the lower limit value within the range of the critical rinsing degree that does not cause resin leakage or stringing. For example, で is set to 5). In a region where the temperature is lower than this judgment value, the chip is ripened by the heating coil and the temperature changes in the rising direction. The rise is slowed or, conversely, a drop in temperature is detected to detect a short shot of the coil. In addition, in the molding region where the temperature is higher than the above-mentioned judgment value, appropriate ripening is performed so as to keep the chip temperature almost constant. In this way, a short shot of the coil is detected.

In the above embodiment, a commutation type circuit was used as the high-frequency power supply circuit 42, in which the supply power increases as the frequency decreases, but the supply power increases as the frequency increases. Larger circuits can also be used. Furthermore, in the above implementation, the S degree control circuit 52 compares the average value of the actual S degrees at the leading ends of the four chips 36a to 36d with the set temperature. Alternatively, the actual temperature at the tip of any one of the chips may be compared with the set S degree.

Claims

(Scope of Claim) Consists of a fixed working half and a movable half, and a plurality of cavities formed when both halves are closed, and the cavities, the nozzles of the molding machine, and the like. A mold having a resin passage for supplying molten resin into each cavity from a gate hole opened in each cavity, and

Ripening means for ripening the resin passage of the mold and keeping the resin in the resin passage in a molten state;

In a hot runner type injection molding apparatus comprising: a pipe-shaped member, at least a portion of each of the resin passages near each gate hole is formed of a material which can be heated by high-frequency induction ripening. A plurality of high-frequency induction heating coils wound around the respective pipe-like members and connected in series with each other; In response to a temperature signal from a high-frequency power supply means for supplying high-frequency power to the coil and a temperature detection means, the frequency power supply means supplies the coil to the low-frequency induction ripening coil. A molding apparatus comprising turbidity control means for controlling electric power to control the temperature of the pipe-shaped member to a desired value.

The claim 1, wherein a frequency of the high frequency power supplied to the high frequency ripening coil by the high frequency power supplying means is 20 kHz to 50 kHz. Description Molding equipment.

The box-shaped enclosure according to claim 1 or 2, wherein each of the high-frequency induction ripening coils is densely wound around the pipe-shaped member at a portion near the gate hole. Molded information described in paragraph 2.

4. The molding apparatus according to claim 3, wherein each of the high-frequency induction ripening coils is sparse at a central portion of the length thereof and densely wound at a distal end portion thereof.

The box-shaped enclosure according to any one of claims 1 to 4, wherein each of the high-frequency induction heating coils is fixed in a spiral groove formed around the pipe-shaped member. The molding apparatus according to item 1.

) Wherein said ripening means is connected in parallel to each of said high frequency induction heating coils to connect a gate-parameter adjusting circuit for changing power distribution to said ripening coil; 2. The molding apparatus according to claim 1, further comprising a gate connection circuit connecting means provided corresponding to the ripening coil.

The ripening means includes switching means for stopping the power supply from the high-frequency power supply means to the high-frequency induction ripening coil at a predetermined cycle at a predetermined time; and The control means reads the temperature signal while the power supply from the high-frequency power supply means to the peripheral induction heating coil is stopped. Special 7. The molding apparatus according to claim 6, wherein

) The high-frequency induction heating coil for a predetermined period of time is supplied with a power larger than the power required to control the temperature of the pipe-shaped member to the desired value by receiving the signal from the molding machine. 8. The molding device according to claim 7, wherein the molding device is supplied to an oil.

The ripening means receives the temperature signal from the temperature detection means, calculates a temperature change rate, and obtains a temperature of the high frequency induction ripening coil from a relationship between the temperature change rate and a temperature based on the temperature signal. 9. The molding apparatus according to claim 8, further comprising a shot detection means for detecting the presence or absence of a shot.

) Each of the high-frequency induction ripening coils is held by a holding member to form a coil assembly, and the holding member is cut between the coil and the outer peripheral surface of the pipe-shaped member. The molding apparatus according to claim 9, wherein the high frequency induction heating coil is held through a mature layer.10) The molding machine according to claim 9, wherein the outer wall of the coil assembly is 10. The molding apparatus according to claim 10, wherein the molding apparatus is in contact with a mold.

The molding apparatus according to claim 11, wherein the coil assembly and the pipe-shaped member are integrally formed.

) The coil assembly is separate from the pipe-shaped member. Molding apparatus Claims ^first 1, wherein said that you are formed.

14) The molding apparatus according to claim 11, wherein the severing employee is an air severing employee.

15) The temperature control means receives a signal from the molding machine, and supplies electric power, which is larger than electric power necessary to control the temperature of the pipe-shaped member to the desired value, only for a predetermined time. 7. The molding apparatus according to claim 6, wherein the apparatus is supplied to a frequency induction heating coil.

16) The ripening means receives the temperature signal from the grip detection means, calculates a temperature change rate, and calculates the fan wave induction from the relationship between the temperature change rate and the temperature based on the mixture signal. 16. The molding apparatus according to claim 15, further comprising a short detecting means for detecting the presence or absence of a short-cut of the ripening coil.

17) The heating means includes switching means for stopping the power supply from the high-frequency power supply means to the high-frequency induction ripening coil at a predetermined time and at a predetermined time. The temperature control means reads the temperature signal while power supply from the high-frequency power supply means to the high-frequency induction heating coil is stopped. The molding device according to claim 1.

18) When the temperature control means receives a signal from the molding machine and controls the temperature of the pipe-shaped member to the desired value. 18. The molding apparatus according to claim 17, wherein a power larger than a required power is supplied to said high-frequency induction heating coil only for a predetermined time.

The ripening means receives the Atsushi degree signal from the temperature detecting means, calculates a grip change rate, and obtains the high frequency induction ripening coil from a relationship between the temperature change rate and a temperature based on the temperature signal. 18. The molding apparatus according to claim 18, further comprising a short detection means for detecting the presence or absence of a short shot of the tool.

) Each of the high-frequency induction ripening coils is held by a holding member to form a coil assembly, and the holding member is in contact with the outer peripheral surface of the pipe-shaped member. 10. The molding apparatus according to claim 19, wherein the high-frequency induction aging coil is held through a ripening step. A temperature change rate is calculated by receiving the temperature signal from the temperature detection means, and the presence or absence of a short circuit of the high frequency induction ripening coil is determined based on a relationship between the temperature change rate and the grip based on the temperature signal. 18. The molding apparatus according to claim 17, further comprising a short-circuit detecting means for detecting the molding.

) The temperature control means receives a signal from the molding machine and applies a power larger than a power required to control the temperature of the pipe-shaped member to the desired value for a predetermined time. Is to supply to the -The molding apparatus according to claim 1.

) The ripening means receives the humidity signal from the seedness detection means, calculates a temperature change rate, and calculates the temperature change rate and the temperature based on the temperature signal based on the relationship between the temperature change rate and the temperature. 23. The molding apparatus according to claim 22, further comprising: a short detection means for indicating whether or not there is a short shot of the tool.

) Each of the high-frequency induction ripening coils is held by a holding member to form a coil assembly, and the holding member is insulated to the outer peripheral surface of the pipe-shaped member through a heat insulating member. 24.The molding apparatus according to claim 23, wherein the high-frequency induction ripening coil is held. A short-circuit detecting means for calculating a temperature change rate in response to the temperature signal, and detecting the presence or absence of a short-circuit of the high-frequency induction heating coil from a relationship between the temperature change rate and a temperature based on the temperature signal; The molding apparatus according to claim 1, wherein the molding apparatus is provided with:

) Each of the high-frequency induction heating coils is held by a holding member to form a coil assembly, and the holding member is placed in a garden with the outer peripheral surface of the pipe-like member through employment. The molding apparatus according to claim 1, wherein the high-frequency induction ripening coil is held by the mold.The outer wall of the coil assembly is the same as the mold. Covered The molding apparatus according to claim 10, wherein:

28. The molding apparatus according to claim 27, wherein the coil assembly and the pipe-shaped member are formed integrally.

29. The molding apparatus according to claim 27, wherein the coil assembly and the pipe-shaped member are formed separately.

30) The molding apparatus according to claim 27, wherein the ripening layer is an air heat insulating layer.